Girls, Should I go up another cup size?

I'm wearing a 30GG (UK sizes) and my boobs are enclosed, but the core doesn't sit flat on my ribs and I can feel the bottom of the cups keeping the girls in as well as they should. Do I need to go to an H?

Updates:

Also, I think I maybe gaining weight, so I thought about trying to lose weight and hope my boobs shrink down a bit XD